As Lee suggests, they're having another manufacturer make them with their label. They simply have to meet their "specifications", whatever they are.
The battery type and chemistry you want will depend on your actual usage. A ten-year shelf-life is pointless if you are using the flashlight regularly, and you're wasting money on a premium battery. But, if it's something you
might use briefly once or twice a year, a long shelf-life is a good thing. (Just be sure to check it occasionally.)
Then there is the question of how long you need to use it each time, and the load. A flashlight has a different load than a camera or another piece of electronics.
The point is, any other battery of the same form-factor "will work", but may not be optimal for your particular usage. If you're going through them fast enough to have already bought replacements a few times, I suggest trying other cheaper name-brands.
(I used to sell batteries, as part of my job, and later worked on advanced battery development.

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